Molding compositions, generally in the form of ceramic masses, must be fabricated in dental technology for a variety of purposes and in accordance with a variety of criteria, especially for the formation of dental prostheses or for the filling of regions in dental prostheses or elsewhere in the dental arcade. Criteria such as texture, color, bonding capabilities and material selection are all important. It is thus understandable that mixing plate systems have been provided heretofore which have a number of troughs which must be supplied by a moisturizing source in a continuous manner to prevent premature drying out of the various mixtures which can have different compositions in the troughs, depending upon the several criteria.
Among the earlier systems is an arrangement in which a porous wicking trough plate is provided which is mounted in a water bath in a tray. In this system, the water level must be carefully controlled so that the underside of the porous trough plate is continuously wetted with water. Adjustment of the water level is effected by addition of water and, since such addition must be done manually and with care, use of the mixing device is time-consuming and prone to problems since it is not difficult to inadvertently add water above the desired level and thereby cause an excessive influx of water into the troughs and damage to the mixtures therein. Furthermore, should the level drop below the desired level, moisturizing of the compositions may come to a sudden halt to the detriment of the compositions which rapidly dry out.
In another earlier mixing arrangement, a water reservoir is provided in a tray beneath the trough plate and individual wicks are provided to carry water from the reservoir through holes in the plate into the troughs when the contents of the troughs can thereby be moistened.
In this system as well, the level of liquid must be maintained with precision to ensure a constant and uniform moistening of the compositions and the direct connection of the reservoir with the mixing plate entails a host of disadvantages. For example, any impact delivered to the apparatus, e.g. as a result of mixing, can give rises to waves in the reservoir and can result in changes in the moistening effect. Such waves damp out only slowly and hence the system is prone to nonuniformities.